<form class="col s12">
  <div class="row">
    <div class="input-field col s6">
      <i class="material-icons prefix">info</i>
      <input id="first_name" type="text" class="validate">
      <label for="first_name">Prénom</label>
    </div>
    <div class="input-field col s6">
      <i class="material-icons prefix">info</i>
      <input id="last_name" type="text" class="validate">
      <label for="last_name">Nom de famille</label>
    </div>
  </div>
  <div class="row">
    <div class="input-field col s12">
      <i class="material-icons prefix">phone</i>
      <input id="Mail" type="email" class="validate">
      <label for="Mail">E-mail</label>
    </div>
  </div>
    <div class="row">
        <form class="col s12">
        <div class="row">
            <div class="input-field col s12">
            <i class="material-icons prefix">chat</i>
            <textarea id="message" class="materialize-textarea"></textarea>
            <label for="message">Message</label>
            </div>
        </div>
<button class="btn waves-effect waves-light" type="submit"
name="action">Envoyer
<i class="material-icons right">send</i>
</button>
        </form>

<?php
if(isset($_POST['submit'])){
$to = "myemail@gmail.com";
$from = $_POST['Mail'];
$first_name = $_POST['first_name'];
$last_name = $_POST['last_name'];
$subject = "Mail subject";
$message = $first_name . " " . $last_name . " à écrit ceci:" . "nn" .
$_POST['message'];

$headers = "From:" . $from;
$headers2 = "From:" . $to;
mail($to,$subject,$message,$headers);
echo "Mail Sent. Thank you " . $first_name . ", we will contact you
shortly.";

}
?>